Actually, this exact rescue plays out almost every year at Wind Cave. It is common for an ice plug to block exit from the cave. What is hard to believe is that so many people will attempt the through trip without checking on the ice plug first, especially since you already have to go in the lower entrance and rig a rope just to get out anyway.

According to newspaper reports the spelunkers knew about the ice plug and although they could have checked it out from the Wind cave entrance they chose not to because it would have involved more effort. They planned to chop their way through and seemingly thought that the possibility of rescue was OK.